build: set up a bootstrap script for all jasmine tests which ensures …

…that the temp directory is cleared

Creating a bootstrap script for jasmine tests allows us to ensure automatically for all
jasmine tests that the temporary directory created for the test runs is cleaned between specs.

ng-dev/utils/testing/BUILD.bazel

@@ -2,9 +2,15 @@ load("//tools:defaults.bzl", "ts_library")
 
 ts_library(
     name = "testing",
-    srcs = glob(["*.ts"]),
-    visibility = ["//ng-dev:__subpackages__"],
+    srcs = glob(
+        ["*.ts"],
+        exclude = ["bazel-env.ts"],
+    ),
+    visibility = [
+        "//ng-dev:__subpackages__",
+    ],
     deps = [
+        ":bazel-env",
         "//ng-dev/utils",
         "@npm//@types/jasmine",
         "@npm//@types/node",
@@ -15,3 +21,17 @@ ts_library(
         "@npm//yargs",
     ],
 )
+
+ts_library(
+    name = "bazel-env",
+    srcs = [
+        "bazel-env.ts",
+    ],
+    visibility = [
+        "//ng-dev/utils/testing:__subpackages__",
+        "//tools/jasmine:__subpackages__",
+    ],
+    deps = [
+        "@npm//@types/node",
+    ],
+)

ng-dev/utils/testing/bazel-env.ts

@@ -6,6 +6,7 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
+import {existsSync, mkdirSync, rmSync} from 'fs';
 import {join} from 'path';
 
 /**
@@ -14,3 +15,14 @@ import {join} from 'path';
  * chmod, or otherwise alter [TEST_TMPDIR]," so a subdirectory path is used to be created/destroyed.
  */
 export const testTmpDir: string = join(process.env['TEST_TMPDIR']!, 'dev-infra');
+
+/**
+ * Prepares the temporary test directory, deleting previous contents if present. Ensures the temp
+ * directory exists.
+ */
+export function cleanTestTmpDir() {
+  if (existsSync(testTmpDir)) {
+    rmSync(testTmpDir, {recursive: true});
+  }
+  mkdirSync(testTmpDir);
+}

tools/defaults.bzl

@@ -1,16 +1,9 @@
-load("@npm//@bazel/jasmine:index.bzl", _jasmine_node_test = "jasmine_node_test")
 load("@npm//@bazel/typescript:index.bzl", _ts_library = "ts_library", _ts_project = "ts_project")
 load("@npm//@bazel/esbuild:index.bzl", _esbuild = "esbuild")
 load("@build_bazel_rules_nodejs//:index.bzl", "generated_file_test", _pkg_npm = "pkg_npm")
+load("//tools/jasmine:jasmine.bzl", _jasmine_node_test = "jasmine_node_test")
 
-def jasmine_node_test(name, specs = [], **kwargs):
-    _jasmine_node_test(
-        name = name,
-        srcs = kwargs.pop("srcs", []) + specs,
-        deps = kwargs.pop("deps", []),
-        use_direct_specs = True,
-        **kwargs
-    )
+jasmine_node_test = _jasmine_node_test
 
 def ts_project(**kwargs):
     _ts_project(

tools/jasmine/BUILD.bazel

@@ -0,0 +1,50 @@
+load("@npm//@bazel/typescript:index.bzl", "ts_library")
+load("//tools:defaults.bzl", "jasmine_node_test")
+
+ts_library(
+    name = "bootstrap_ts",
+    testonly = True,
+    srcs = [
+        "bootstrap.ts",
+    ],
+    visibility = ["//visibility:public"],
+    deps = [
+        "//ng-dev/utils/testing:bazel-env",
+        "@npm//@bazel/jasmine",
+        "@npm//@types/jasmine",
+    ],
+)
+
+alias(
+    name = "bootstrap_dependencies",
+    actual = "//ng-dev/utils/testing:bazel-env",
+    visibility = ["//visibility:public"],
+)
+
+filegroup(
+    name = "bootstrap",
+    testonly = True,
+    srcs = [":bootstrap_ts"],
+    output_group = "es5_sources",
+    visibility = ["//visibility:public"],
+)
+
+ts_library(
+    name = "bootstrap_test",
+    testonly = True,
+    srcs = [
+        "bootstrap.spec.ts",
+    ],
+    deps = [
+        ":bootstrap_ts",
+        "//ng-dev/utils/testing:bazel-env",
+        "@npm//@types/node",
+    ],
+)
+
+jasmine_node_test(
+    name = "test",
+    specs = [
+        ":bootstrap_test",
+    ],
+)

tools/jasmine/bootstrap.spec.ts

@@ -0,0 +1,44 @@
+/**
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+import {readFileSync, writeFileSync} from 'fs';
+import {join} from 'path';
+import {testTmpDir} from '../../ng-dev/utils/testing/bazel-env';
+
+describe('bootstraping script', () => {
+  // This specific describe block is explicitly testing that
+  jasmine.getEnv().configure({
+    ...jasmine.getEnv().configuration(),
+    random: false,
+  });
+
+  /** A randomized string to write into the file to confirm it was removed. */
+  const testContent = `This is random: ${Math.random()}`;
+  /** The absolute path to a file within the temporary test directory. */
+  const testFilePath = join(testTmpDir, 'test-file');
+  /** The number of tests which have run within the describe block. */
+  let testCount = 0;
+
+  it('allows files in the temp directory to be modified', () => {
+    // The postfix increment operator is used to check the current value, while incrementing by 1.
+    expect(testCount++).toBe(0);
+    // Write the test content to the a file in the temporary test directory.
+    writeFileSync(testFilePath, testContent);
+
+    expect(readFileSync(testFilePath, {encoding: 'utf8'})).toBe(testContent);
+  });
+
+  it('ensures the files created in previous tests are not kept between specs', () => {
+    // The postfix increment operator is used to check the current value, while incrementing by 1.
+    expect(testCount++).toBe(1);
+    /** A matcher for a file not existing at the path provided. */
+    const errorMatcher = new RegExp(/^ENOENT\: no such file or directory, open/);
+
+    expect(() => readFileSync(testFilePath, {encoding: 'utf8'})).toThrowError(errorMatcher);
+  });
+});

tools/jasmine/bootstrap.ts

@@ -0,0 +1,25 @@
+/**
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+import {cleanTestTmpDir} from '../../ng-dev/utils/testing/bazel-env';
+
+/**
+ *  The `boot` utility function from `@bazel/jasmine` allows initialization before the runner, with
+ *  protections to prevent calling `boot` again.
+ */
+const {boot} = require('@bazel/jasmine');
+
+// Initialize jasmine, because beforeEach and other jasmine "globals" are not defined in the
+// environment until jasmine has been initialized.  Since our bootstrap explicitly is meant to use
+// these globals, we need to ensure that jasmine has already initialized before the major content
+// of our script executes.
+boot();
+
+beforeEach(() => {
+  // Before each spec runs, clean the temporary test dir to prevent specs from effecting each other.
+  cleanTestTmpDir();
+});

tools/jasmine/jasmine.bzl

@@ -0,0 +1,21 @@
+load("@npm//@bazel/jasmine:index.bzl", _jasmine_node_test = "jasmine_node_test")
+
+def jasmine_node_test(name, specs = [], **kwargs):
+    templated_args = kwargs.pop("templated_args", []) + [
+        # Include our jasmime bootstrap file to be run before the jasmine runner.
+        "--node_options=--require=$$(rlocation $(rootpath //tools/jasmine:bootstrap))",
+    ]
+
+    _jasmine_node_test(
+        name = name,
+        srcs = kwargs.pop("srcs", []) + specs,
+        use_direct_specs = True,
+        deps = kwargs.pop("deps", []) + [
+            "//tools/jasmine:bootstrap",
+            # Because we don't provided a bundled script, we must ensure that the dependencies for
+            # bootstrap are also included as dependencies.
+            "//tools/jasmine:bootstrap_dependencies",
+        ],
+        templated_args = templated_args,
+        **kwargs
+    )